We were never resetting the dead state for repaired SAMs. Rather than
tracking that manually, determine liveness from the number of units left
alive.
For building objectives where the group is not assigned to the TGO until
*mission* generation time we still need manual tracking.
(cherry picked from commit d3b1f6110f)
When a base is captured we clear its defenses. Those locations need to
be returned to the preset location pool so they can be used for the new
base defenses.
Like with deleting waypoints, these will degrade the flight plan to the
2.1 behavior.
Ascend/descend points aren't in use any more, so I removed those.
